Geoheritage sites of India

It is said that Geology starts where history and archeology ends.Apart from having rich cultural diversity India has a rich geodiversity.

Ironically, on the one hand, we reach out to Mars in search of evidence for early life, but on the other, we destroy such evidence that is so precious and right in our backyard. How many of us know about the little known Dhala meteoritic impact crater in Shivpuri, Madhya Pradesh, a 1.5-2.5 million year old preserved as a mark of a celestial collision when life must have just begun? (The more famous Lonar crater in Buldhana district of Maharashtra was dated to be about 50,000 years old). Or for that matter the 236,000-year old female Homo species discovered in Hathmora, Madhya Pradesh? Scientists initially called the fossil the “Narmada Man”, but this was a mistake; they later turned out to be that of a woman 27-32 years old.
These are spectacular to look at even for the general public who may not understand that they are also geologically important. Lonar lake is the only known meteorite crater in basaltic rock and is world famous, while St. Mary’s island is a unique phenomenon that has been preserved well as St.Mary’s Island,  is estimated to be an 88-million-year-old formation that goes back to a time when Greater India broke away from Madagascar.

The unique geographic entity of Kutch in Gujarat and its vicinity contains dinosaurian fossils of the Mesozoic age (200 million years ago). However, many scientifically informative geological sections in that region that preserve the signatures of early Earth have been lost forever due to the construction of highways and real-estate development.

The Trichinopoly region of Tamil Nadu was originally a Mesozoic ocean. Now a veritable store house of Cretaceous (60 million years ago) marine fossils is in a state of decline thanks to both legal and illegal activities.

What is geodiversity? 

 The diversity found in geological formations of the earth such as rocks, fossils, minerals and 

geological processes that create distinctive formations is known as Geodiversity. It is the 

major abiotic component supporting landscapes, biodiversity, and ecosystems. Studying these allow us to trace the evolutionary history and understand its natural environment for better resource management.

What is geoheriage?

Geodiversity is entitled to as Geoheritage when a certain uniqueness or value is attributed 
to it. The Geoheritage sites encompass significant elements which possess educational, scientific, aesthetic and cultural value. These features are vulnerable as once destroyed cannot be recreated.

Geological Survey of India [GSI] –one of the oldest in the world founded on 1851, is the 
parent body which is making efforts towards identification and protection of such rare and 
unique geological sites in India.  It has recognised  26 National geological monuments(NGM) in 2001. We are yet to see a concerted strategy from officials to this end. A major challenge for Indian geologists, including the Geological Survey, is the nonexistence of a complete inventory of geological structures in the country.NGMs have been classified into four categories namely Fossil Parks, Rock Monuments, Geological Marvels and other monuments based on Stratigraphic and
Economic importance.  Sadly, beyond declaration little else has been done to protect and conserve this inheritance.

Geo-heritage sites in many countries have been developed as geo-parks. Canada, China, Spain, the US and the UK have suitable provisions for the preservation and conservation of their national geo-heritage. UNESCO has also prepared guidelines for the development of geo-parks. Many countries also have the necessary legislation to build, protect and designate geo-parks .Geo parks are that geoheritage sites which is a larger area incorporating more unique natural geographical formation and  have the scope of tourism and recreational activities.Large area is converted to geo parks aimed at general public involvement in geology things.
General public may not be aware of geological marvelous but absolutely love the unique formations

Let's go to a  such a tour

Natural Arch, Tirumala Hills ,Andhra pradesh

Natural archs are formed after the cliffs are subjected to various erosion activities.
This Arch is said to be carved out of Nagari quartzite of Cuddapah Super Group of Middle to Upper Proterozoic (1600 to 570 Ma). The age of arch is estimated to be 1500 million year.
Similar arch is carved out from khondalite rocks  of eastern ghats by the wave actions of sea from bay of bengal in vishakhapattanam.

2 Eparchean Unconformity,Tirumala hills ,A.P

Eparchaean Unconformity (period of no rock deposition) in Tirumala hills separates the Nagari Quartzites of Proterozoic  Kadapa Supergroup (about 1600 million year) from the oldest Archean Peninslular Gneissic complex consisting of granites, gneisses and dolerite dykes (more than 2300 million years old). The unconformity represents a time gap of over 800 Ma. It also marks a period of remarkable quiescence without much structural disturbance and igneous activity in geological history.  It lies very close to Natural archs.

Between  these  geological  eras,  at  times  there  were  gaps  in  the  accumulation  of  rock  masses or  occasionally  the  pre-existing  rocks  were  subjected  to  weathering  and  denudation.  This resulted  in  a  boundary  between  the  older  and  the  younger  rocks  which  therefore  indicate  a period  of  non-deposition/erosion  demonstrating  an  unconformity.    After  Archean  Era,  there was  no  deposition  of  rocks  and  the  land  mass  was  subjected  to  erosion  for  millions  years. The  geological  process  was  followed  by  formation  of  Proterozoic  rocks.  This  time  gap between  the  Archean  and  Proterozoic  rocks  is  known  as  Eparchean  unconformity.

3.Bedded  Barytes,  Mangampeta,YSR  District

Barytes  Deposits  in  Mangampeta Bedded  is  the  largest  barytes  deposit  in  the  world about  98%  of  India’s  barytes    and  28%  of  world’s  barites  reserves which  occur  as  pure barium sulphate .It is situated  in  the  crescent  shaped  Cudddapah  basin  of  Proterozoic era.
Barytes is naturally occurring barium sulphate. Barytes deposits have formed over time due to precipitation of volcanic vapours under submarine conditions, sub-aerial showering of ash and molten baryte lapilli. The deposits occur as Pullampet Formation of the Nallamalai Group of the Cuddapah Supergroup). The lower bed has Mangampeta Barytes which is considered as the highest grade of barium sulphate.

4. Marine  Gondwana Fossil  Park, Chattisgarh

Spread  across  an  area  of  16,200  sq  m,  the  park  is characterized  by  the  unique exposure  of  fossiliferous  marine  Permian  (280  –  240  Ma)  Carbonaceous shale rocks  of Talchir  Formation  belonging  to  Gondwana  Supergroup.
There is a large granite intrusion in fossil park.

5 Eddy Current Markings, Gujrat

It consists of petrified markings on sandstone-quartzite surface from Upper Aravalli Lunavada Group (Precambrian- Proterozoic). It is one of rarest geological marvel representing the geology and evolution of Aravali

6.Siwalik Fossil Park, Saketi,Himachal pradesh

This centre  is  situated  amidst  10  to  1.5  million  year  old  (Middle  Miocene  -  Early Pleistocene)  rocks  of  the  Siwalik  Group  with  rich  assemblage  of  vertebrate  fossils.   Beginning  with  coarse  sandstone  and  culminating  in  red,  yellow  and  carbonaceous  grey  clay,  nearly  40 sedimentary  cycles,  have  been  counted  in  the  240m  thick  sequence  of  Saketi  Formation.  

The  strata  is   mainly  made  up  of  alternating  layers  of  variegated  clay,  mudstone,  siltstone.The  unit  has  yielded  a  rich  vertebrate  assemblage  consisting  of  conglomeration  of  both  land  and aquatic  vertebrate  group.  The  assemblage  of  fossils  includes  that  of  elephant,  alligator,  giraffe, hippopotamus,  camel,  rhino  etc.  The  topmost  100m  thick  sequence,  variegated  clay  dominant  facies  of this  formation,  is  particularly  rich  in  fossils  as  it  yielded  the bulk of fossil material.